1. Field of the Invention
The present invention relates to a broadband wireless communication system. More particularly, the present invention relates to an apparatus and method for allocating a preamble index to a Self Configurable-Base Station (SC-BS) in a broadband wireless communication system.
2. Description of the Related Art
Recently, research efforts have focused on developing a wireless communication system that can transmit a large amount of data at high speed. For that purpose, several different concepts are being considered. For example, concepts such as the reduction of a cell size to increase system throughput, the employing of a smaller Base Station (BS) that has a lower price, the employing of an indoor BS for office and home, and other concepts are being considered. In the case that the smaller BS is employed, a function for the automatic installation of a BS and a function for recognizing a change in the configuration of adjacent BSs are needed to make frequent installation and de-installation of the small BSs easier. Accordingly, in the 3rd Generation Partnership Project Long-Term Evolution (3GPP LTE), these functions are referred to as self organization and are in the process of standardization.
A BS must transmit a preamble signal for frame synchronization for proper operation as a BS. Because preamble signals from a plurality of BSs should be distinguished from each other, a preamble index is used to distinguish the preamble signals. The preamble index consists of a segment IDentifier (ID) and an ID cell and is related to a preamble code, scrambling and sub-channelization. If adjacent BSs use the same preamble index, strong interference occurs between preamble signals of the BSs. Therefore, the preamble indexes should be allocated appropriately.
Generally, the preamble indexes are set by the system designer when the BSs are installed. However, in the case of a Self Configurable-BS (SC-BS) having an automatic installation function and an automatic network optimization function, a preamble index for the SC-BS is allocated adaptively while a system is working. The preamble index for the SC-BS is allocated adaptively because the SC-BS is installed based on a user's needs. Furthermore, it is expected that the SC-BS is installed in an indoor environment, thus an amount of interference affecting the SC-BS fluctuates widely. Accordingly, there is a need to provide a proper solution to allocate a preamble index to an SC-BS considering an indoor environment and a surrounding radio environment.